Treatment of artificial silk



Patented July 4, 1939 TREATDIENT OF ARTIFICIAL SILK Alfred E. Sunderland, Asheville, N. 0., assignor to- I American Enka Corporation, Enka, N. 0., a corporation of Delaware No Drawing.

Application January 5, 1937, Serial No. 119,160

9 Claims. (01. 28-1) This invention relates to the treatment of threads, yarns, filaments and the like of artificial origin. More particularly, the invention involves a specific treating step in the production of rayon threads for use in crepe effect fabllCS.

In order to prevent threads from curling or crimping after they have been subjected to the high twist normally imparted thereto for the purpose of producing crepe effects, it is well known to employ various sizing compositions. These compositions act to induce a set in the twist and also properly lubricatethe thread for the subsequent fabricating operations. In general, the more commonly used sizing compositions for impregnating threads of artificial origin consist of preparations containing gums, gelatin, starch and the like. These preparations often also contain oils in order to lubricate the thread and render the same more pliable or supple. The sizing step is a standard operation in the artificial silk industry when preparing threads for crepe fabric, and may be carried out by the yarn producer at the time of manufac- 25 ture; but it is the more common practice to ship the finished thread having only a low twist (from 3 to 5 turns per inch) to the fabric manufacturer. When this latter practice is adopted, the fabric manufacturer applies the sizing agent to the thread prior to the high twisting operation after which the yarn is fabricated into crepe effect cloth.

In order to illustrate the novelty of my invention, it is necessary to describe one of the most common methods, normally used for the processing of rayon yarns by the throwster and weaver for'the production of crepe fabrics. This general method consists of impregnating the rayon with a solution such as a mixture of gelatin and soluble oil or an emulsion of wax. This treatment is termed sizing the rayon yarn. The yarn is then dried. The sized rayon yarn is high- 1y twisted, usually about 50 turns per inch, and the twisted rayon yarn is steamed for some hours and allowed to cool. The action of the sizing agent is that it softens in the steaming,

- fills up the hollows in the twist, and on cooling,

stifiens again, thus preventing the twist from asserting itself. When the rayon yarn is woven into fabrics, the sizing binder is removed by hot water and soap; the twist, then unwinding. causes the crepe appearance.

In contra-distinction to the sizing step, and as an entirely separate operation from the foregoing, my present inv ntion c nt p ates a method of treating threads of artificial origin with a chemical compound which on subsequent drying is renderedinsoluble. The properties of this precipitated composition is such that the thread so treated will exhibit increased resistance to radialtorque. The advantages of this property will be hereinafter more fully explained. Furthermore, this treatment is such that the rayon does not become stiff, but retains its normal soft and pliable character unimpaired.

Whereas the following detailed description is specific to the treatment of threads manufactured according to the viscose process, it is intended that the scope of my invention be limitative only to the extent of treating artificial threads which are water absorbent.

According to my present invention an alkali cellulose solution is extruded'to form threads consisting of a plurality of filaments. These threads are processed and finished in the usual manner. The processed and slightly twisted threads normally ready for shipment to the crepe fabric manufacturer are now impregnated in either wet or dry state, but preferably in a wet condition, with a very weal: solution of egg albumen. The treating step may even be combined with the usual final washing operation.

In preparing the albumen solution very small quantities are dissolved in pure water. The maximum amount which will effect the improved novel results is only one part of albumen to two hundred parts of water and, in fact, the best results have been obtained by utilizing a solution having one part of albumen to four thousand parts of water. It is a surprising observation that if too much albumen is used, ill effects become evident in that a stiffer yarn is produced which'is not desirable for the production of crepe eil'ect fabric.

After the thread is treated with the albumen 1 solution, it is dried at the normal drying temperatures, which are suflicient to render the albumen insoluble on the surface of the thread. In this condition the thread is in readiness for shipment to the crepe fabric manufacturer and can then be processed by any of the customary methods normally employed. This includes the application of the crepe sizing composition.

Upon examination, it has been determined that the physical change produced by the use of such a small amount of albumen does not afiect the strength or elongation properties of the ..thread. In addition, no change can be detected in the crepe twisted thread, either with respect tothe; twist take-up, or the shrinkage pr perties. The

' in resistance to the radial or twisting torque.

- plete impregnation, the silk ishydroextracted and The improved novel effect resulting from this property becomes apparent when the entire process is taken into consideration. The albumen is insoluble and is retained on and in the thread when the sizing composition is applied. After the thread has been given a high twist and the cloth has been fabricated, the size used in the twisting operation is removed by hot water, but the albumen coating remains intact. As stated before, the size sets the twist, which, upon removal, allows the woven threads to untwist and create the pebble effect, or disturbance in the surface of the cloth, which is the basic property of all crepe fabrics. The prior addition of albumen in minute quantities increases the untwisting effect so that removal of the size causes an improved and superior pebble, or increased disturbance, in the surface of the fabric.

Among the various sizing compositions which have been used, casein and albumen have been mentioned. However, in all such cases they have been employed in combination with other sizing agents and in relatively large quantities. It is to be noted that my improved process bears no relationship whatsoever to those sizing operations. Neither does it take the place of this step nor prohibit the use of any of the usual methods of treatment for crepe twisting.

It may be desirable to substitute other adhesive substances for albumen, but such substances must have the necessary prerequisites such as becoming insoluble when heated to the temperatures normally employed for drying artificial silk. Moreover, the substances must remain in or on the thread when the size is removed. Examples of substances which may be used are gum tragacanth, gum tragon and the mucous solutions obtained from the outer coverings of seed such as linseed.

I have found that the maximum and minimum limits to be employed may vary from one part of albumen or its equivalent and two hundred parts of water to one part of albumen or its equivalent and ten thousand parts of water, respectively. The preferred ranges, however. consist of. one part of albumen and five hundred parts of water to one part of albumen and four thousand parts of water.

The actual amount of dried albumen or its equivalent left in the thread is based on and is determined by the per cent of solution remaining after hydroextraction. It has been calculated by experiment that this quantity remaining is approximately 65%. Therefore, the dried thread contains 65% of the per cent concentration of the solution employed.

A specific example of utilizing'my' invention involves immersing one hundred pounds of viscose artificial silk in six hundred; pounds of water containing in solution one-pound of white egg albumen (0.167% solution). After comdried at a temperaturesuflicient to render the albumen insoluble. The amount of albumen left in the thread is 0.108%. Having thus described my invention, what I claimis': 1. In the treatment of substantially water-absorbent artificial silk threads for use in the manufacture of crepe eflect fabrics, the step which comprises increasing the resistance of threads to radial torque by permanently impre gnating the threads prior to their fabrication with an aqueous solution of a'substance which is rendered insoluble after drying the threads, said solution having a concentration of less than one part of solute to flve hundred parts of water.

2. In the treatment of artificial silk threads for use in the manufacture of crepe efiect fabrics, a process for improving the creping properties of the threads which comprises preparing an aqueous solution of a substance of the class consisting of albumen, gum tragacanth, gum tragon and mucous solutions obtained from seed coverings, increasing the resistance of the threads to radial torque by permanently impreg nating the same with the solution which solution has a concentration of less than one part solute to two hundred parts water and drying the threads at a temperature sufficient to render the substance insoluble.

3. A treated artificial silk thread for use in the manufacture of crepe effect fabrics and having an increased resistance to radial torque, comprising a water absorbent core of cellulosic origin permanently impregnated with a soluble substance rendered insoluble by drying the core, said substance being in a range of from 0.13% to 0.016% based on the weight of the core.

4. A dried treated artificial silk thread for use in the manufacture of. crepe effect fabrics and having an increased resistance to radial torque,

comprising a water absorbent core of cellulosic origin permanently impregnated with precipitated albumen in a range of 0.130% to 0.016% based on the weight of the core.

5. A treated artificial silk thread for use in the manufacture of crepe effect fabrics and having an increased resistance to radial torque, comprising a water absorbentcore of cellulosic origin permanently impregnated with a 0.025% solution of albumen rendered insoluble by drying the core.

6. In the treatment of substantially water absorbent artificial silk threads for use in the manufacture of crepe effect fabrics, a process for improving the creping properties of. the thread which comprises preparing an aqueous solution of albumen said solution being in a range of from one part albumen and five hundred parts water to one part albumen and four thousand parts water, permanently impregnating the threads with said solution and drying the same at a temperature suflicient to render the albumen insoluble whereby the threads will exhibit an increased resistance to radial torque.

7. A process of preparing viscose artificial silk threads for use in the manufacture of crepe effect fabrics which comprises immersing the threads in an albumen solution of 0.167% concentration, after complete and permanent impregnation, hydroextracting and drying the threads at a temperature suflicient to render insoluble the remaining 0.108% albumen based on the weight oi. the thread'whereby an improved crepe effect fabric is produced.

8;'A method for manufacturing crepe effect fabrics from previously" processed, slightly twisted, water'absorbent thread which comprises impregnating such thread witha weak solution of a substance of. the class consisting of albumen, gumtragacanth, gum tragon and mucous solutions obtained from seed coverings, that is rendered insoluble upon drying the thread said substance being'in a concentration of less than one part to two hundred parts water, applying a sizing preparation, giving the thread a high twist, and fabricating the same into cloth, removing the size while retaining the insoluble substance, said insoluble substance increasing the untwisting eflect of the thread, thereby creating an improved disturbance and pebble in the surface of the fabric.

9. In the treatment of artificial silk threads for use in the'manufacture of crepe effect fabrics, a process for improving the creping properties of the thread which comprises preparing an aqueous solution of a substance of the class consisting of albumen, gum tragacanth, gum tragon and mucous solutions obtained from seed coverings, increasing the resistance of the thread to radial torque by permanently impregnating the same with the solution, which solution is in a concentration of from one part solute and five hundred parts water to one part solute and four thousand parts water, and drying the thread at a temperature suflicient to render the substance insoluble.

ALFRED E. SUNDEBLAND. 

